GNGTS 2018 - 37° Convegno Nazionale

184 GNGTS 2018 S essione 1.2 on sea level indicators in the 0-20 m elevation range, which are rather continuously exposed along the rocky headlands of the study region. Field surveys have allowed us to: (1) identify and characterise different kinds of sea-level markers such as tidal notches, abrasion platforms and lithophaga holes bands, and (2) perform, at each study site (themain outcrops are shown inFig.1), detailed relative chronology reconstructions of erosional/depositional events based on cross cut relationships between continental and marine landforms and deposits. Elevations of sea-level markers were accurately measured and both corals ( Cladocora caespitosa ) and calcite concretions associated with the paleo-shorelines were sampled in order to get new age constraints on the paleo-sea level markers. In order to select corals with a calcite content<5% for uranium-thorium dating, XRPD qualitative vs. quantitative analyses were carried out. In fact, high calcite content means that the corals have lost their original aragonitic shells due to recrystallization processes. In the Grotta del Prete, Scalea (Fig.2) and Marina di Maratea sites (Fig.1) biocalcarenite deposits bearing Cladocora caespitosa present low calcite content (<3%). All of the parameters ( 230 Th/ 232 Th activity ratios, total uranium content of corals, 234 U/ 238 U) derived by the U-series analyses confirm the good quality of the results. Consistency of U-series data is indirectly confirmed by correlation of both dated corals with warm substages of the Late Pleistocene, and dated speleothems with cold stages of the late Quaternary. The combined geomorphological and stratigraphical data have allowed both correlation of coral-bearing deposits with distinct shorelines and reconstruction of morphostratigraphical positions of speleothems. Based on relative chronology reconstructed, at each of the study site, among erosional sea-level markers (e.g., tidal notches, wave-cut platforms), shallow marine and continental deposits (e.g., marine pebbles and/or bioconstructions, and speleothems, respectively), on spatial correlations between paleoshorelines identified at each site, and on geochronological constraints, a relative sea-level curve has been reconstructed for the study region. Notwithstanding some uncertainties on both vertical position of some sea-level markers and correlation between all the identified shorelines with eustatic peaks, our results suggest that sea level rises of the late substages of the Last Interglacial (namely MIS5c and MIS5a) reached paleo-elevation quite close to each other. Such a finding is consistent with evidence from stable areas in the western Mediterranean (e.g., Balearic island, Bardají et al. , 2009). Moreover, at least two distinct sea-level peaksare identified during MIS5a, as already evidenced in southern Calabria by Dumas et al. (2005). Assuming as reference values (with related uncertainties) eustatic sea level paleo-elevations of MIS5 and MIS3 inferred from stable areas of western Mediterranean (Balearic island; Bardají Fig. 2 - View of the wave-cut platforms in the Scalea site .